Wednesday, October 4, 2017

Docker storage options

There are 2 options for storing data:
  • Within the container on its own filesystem - Not recommended for write heavy workloads
  • Outside the container

There are 3 options for mounting data from docker host:
  • Volumes
  • Bind mount
  • Tmpfs mount


  • Stored on host filesystem
  • Managed by docker (/var/lib/docker/volumes/
  • Option recommended by docker
  • Can create named volumes or anonymous volumes
  • Support use of volume drivers that allow you to write data outside container. For eg Flocker, Convoy, sshfs etc See list here
  • Good option when sharing data between containers
  • Reference:

Bind mounts

Tmpfs mount

Performance Difference

Following shows performance of different mount options on Ubuntu instance on AWS t2.micro. (Doesn't include volume driver option as it will vary from driver to driver). Look for kB/s or MB/s

On host
ubuntu@host:~/nks$ sudo time dd if=/dev/zero of=/home/ubuntu/nks/out.txt bs=512 count=1000 oflag=dsync
1000+0 records in
1000+0 records out
512000 bytes (512 kB, 500 KiB) copied, 1.91264 s, 268 kB/s
0.02user 0.00system 0:01.91elapsed 1%CPU (0avgtext+0avgdata 2032maxresident)k
0inputs+8000outputs (0major+82minor)pagefaults 0swaps

Named volume
ubuntu@host:~/nks$ sudo docker volume create my-vol
ubuntu@host:~/nks$ sudo docker volume ls
local               my-vol
ubuntu@host:~/nks$ sudo docker run --rm --net=none --log-driver=none --read-only -v "my-vol:/nks" ubuntu bash -c "time dd if=/dev/zero of=/nks/out.txt bs=512 count=1000 oflag=dsync"
1000+0 records in
1000+0 records out
512000 bytes (512 kB, 500 KiB) copied, 1.90823 s, 268 kB/s

real 0m1.909s
user 0m0.000s
sys 0m0.028s

Host bind mount

ubuntu@host:~/nks$ sudo docker run --rm --net=none --log-driver=none --read-only -v "/home/ubuntu/nks:/nks" ubuntu bash -c "time dd if=/dev/zero of=/nks/out.txt bs=512 count=1000 oflag=dsync"
1000+0 records in
1000+0 records out
512000 bytes (512 kB, 500 KiB) copied, 2.10316 s, 243 kB/s

real 0m2.104s
user 0m0.028s
sys 0m0.000s

tmpfs mount

ubuntu@host:~/nks$ sudo docker run --rm --net=none --log-driver=none --read-only --mount type=tmpfs,destination=/nks ubuntu bash -c "time dd if=/dev/zero of=/nks/out.txt bs=512 count=1000 oflag=dsync"
1000+0 records in
1000+0 records out
512000 bytes (512 kB, 500 KiB) copied, 0.000757215 s, 676 MB/s

real 0m0.001s
user 0m0.000s
sys 0m0.000s

Storing data within container

  • Data is not persistent across container lifecycle
  • Inefficient for write heavy workloads due to disk block allocation and write through storage drivers
  • Pick driver that works best for you. Choice may be limited by the OS.
  • Reference:

Wednesday, September 13, 2017

Build nginx from source on AWS EC2

Launch a new EC2

Type: t2.small (t2.micro may also be fine)
AMIUbuntu Server 16.04 LTS (HVM), SSD Volume Type - ami-6e1a0117

Configure nginx repository

ubuntu@ubuntu:sudo su
root@ubuntu:edit /etc/hosts and add entry for hostname to ip
root@ubuntu:cd /opt
root@ubuntu:add-apt-repository ppa:nginx/stable
edit /etc/apt/sources.list.d/nginx-ubuntu-stable-xenial.list and uncomment deb-src line
root@ubuntu:apt-get update

Install nginx dependencies and get source

root@ubuntu:apt-get build-dep nginx

root@ubuntu:/opt# apt-get source nginx
Reading package lists... Done
NOTICE: 'nginx' packaging is maintained in the 'Git' version control system at:
Please use:
git clone
to retrieve the latest (possibly unreleased) updates to the package.
Need to get 1,835 kB of source archives.
Get:1 xenial/main nginx 1.12.1-0+xenial0 (tar) [981 kB]
Get:2 xenial/main nginx 1.12.1-0+xenial0 (diff) [849 kB]
Get:3 xenial/main nginx 1.12.1-0+xenial0 (dsc) [4,187 B]
Fetched 1,835 kB in 1s (924 kB/s)
gpgv: Signature made Wed 12 Jul 2017 11:41:54 PM UTC using RSA key ID F569EF55
gpgv: Can't check signature: public key not found
dpkg-source: warning: failed to verify signature on ./nginx_1.12.1-0+xenial0.dsc
dpkg-source: info: extracting nginx in nginx-1.12.1
dpkg-source: info: unpacking nginx_1.12.1.orig.tar.gz
dpkg-source: info: unpacking nginx_1.12.1-0+xenial0.debian.tar.xz
dpkg-source: info: applying 0002-Make-sure-signature-stays-the-same-in-all-nginx-buil.patch
dpkg-source: info: applying 0003-define_gnu_source-on-other-glibc-based-platforms.patch
W: Can't drop privileges for downloading as file 'nginx_1.12.1.orig.tar.gz' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permission denied)
root@ubuntu:/opt# ls 
nginx-1.12.1  nginx_1.12.1-0+xenial0.debian.tar.xz  nginx_1.12.1-0+xenial0.dsc  nginx_1.12.1.orig.tar.gz

Build nginx (debian package)

root@ubuntu:/opt/nginx-1.12.1# cd nginx-1.12.1/
root@ubuntu:/opt/nginx-1.12.1# dpkg-buildpackage -uc -b
dpkg-buildpackage: source package nginx
dpkg-buildpackage: source version 1.12.1-0+xenial0
dpkg-buildpackage: source distribution xenial
dpkg-buildpackage: source changed by Thomas Ward
dpkg-buildpackage: host architecture amd64
 dpkg-source --before-build nginx-1.12.1
 debian/rules clean
dh clean --with systemd
   debian/rules override_dh_clean
make[1]: Entering directory '/opt/nginx-1.12.1'
if [ -s /opt/nginx-1.12.1/debian/modules/nginx-cache-purge/.pc/applied-patches ]; then \
cd /opt/nginx-1.12.1/debian/modules/nginx-cache-purge && QUILT_PATCHES=/opt/nginx-1.12.1/debian/modules/patches/nginx-cache-purge quilt pop -q -a; \
dpkg-deb --build debian/nginx ..
dpkg-deb: building package 'nginx' in '../nginx_1.12.1-0+xenial0_all.deb'.
dpkg-deb --build debian/nginx-doc ..
dpkg-deb: building package 'nginx-doc' in '../nginx-doc_1.12.1-0+xenial0_all.deb'.
dpkg-deb --build debian/nginx-common ..
dpkg-deb: building package 'nginx-common' in '../nginx-common_1.12.1-0+xenial0_all.deb'.
dpkg-deb --build debian/nginx-full ..
dpkg-deb: building package 'nginx-full' in '../nginx-full_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/nginx-light ..
dpkg-deb: building package 'nginx-light' in '../nginx-light_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/nginx-extras ..
dpkg-deb: building package 'nginx-extras' in '../nginx-extras_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-geoip ..
dpkg-deb: building package 'libnginx-mod-http-geoip' in '../libnginx-mod-http-geoip_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-image-filter ..
dpkg-deb: building package 'libnginx-mod-http-image-filter' in '../libnginx-mod-http-image-filter_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-xslt-filter ..
dpkg-deb: building package 'libnginx-mod-http-xslt-filter' in '../libnginx-mod-http-xslt-filter_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-mail ..
dpkg-deb: building package 'libnginx-mod-mail' in '../libnginx-mod-mail_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-stream ..
dpkg-deb: building package 'libnginx-mod-stream' in '../libnginx-mod-stream_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-perl ..
dpkg-deb: building package 'libnginx-mod-http-perl' in '../libnginx-mod-http-perl_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-auth-pam ..
dpkg-deb: building package 'libnginx-mod-http-auth-pam' in '../libnginx-mod-http-auth-pam_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-lua ..
dpkg-deb: building package 'libnginx-mod-http-lua' in '../libnginx-mod-http-lua_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-ndk ..
dpkg-deb: building package 'libnginx-mod-http-ndk' in '../libnginx-mod-http-ndk_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-nchan ..
dpkg-deb: building package 'libnginx-mod-nchan' in '../libnginx-mod-nchan_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-echo ..
dpkg-deb: building package 'libnginx-mod-http-echo' in '../libnginx-mod-http-echo_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-upstream-fair ..
dpkg-deb: building package 'libnginx-mod-http-upstream-fair' in '../libnginx-mod-http-upstream-fair_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-headers-more-filter ..
dpkg-deb: building package 'libnginx-mod-http-headers-more-filter' in '../libnginx-mod-http-headers-more-filter_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-cache-purge ..
dpkg-deb: building package 'libnginx-mod-http-cache-purge' in '../libnginx-mod-http-cache-purge_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-fancyindex ..
dpkg-deb: building package 'libnginx-mod-http-fancyindex' in '../libnginx-mod-http-fancyindex_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-uploadprogress ..
dpkg-deb: building package 'libnginx-mod-http-uploadprogress' in '../libnginx-mod-http-uploadprogress_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-subs-filter ..
dpkg-deb: building package 'libnginx-mod-http-subs-filter' in '../libnginx-mod-http-subs-filter_1.12.1-0+xenial0_amd64.deb'.
dpkg-deb --build debian/libnginx-mod-http-dav-ext ..
dpkg-deb: building package 'libnginx-mod-http-dav-ext' in '../libnginx-mod-http-dav-ext_1.12.1-0+xenial0_amd64.deb'.
 dpkg-genchanges -b >../nginx_1.12.1-0+xenial0_amd64.changes
dpkg-genchanges: binary-only upload (no source code included)
 dpkg-source --after-build nginx-1.12.1
dpkg-buildpackage: binary-only upload (no source included)

Verify the build output

root@ubuntu:/opt/nginx-1.12.1# ls -l ../
total 4084
-rw-r--r--  1 root root  28526 Sep 13 21:51 libnginx-mod-http-auth-pam_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  30820 Sep 13 21:51 libnginx-mod-http-cache-purge_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  30218 Sep 13 21:51 libnginx-mod-http-dav-ext_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  39874 Sep 13 21:51 libnginx-mod-http-echo_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  33470 Sep 13 21:51 libnginx-mod-http-fancyindex_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  29760 Sep 13 21:51 libnginx-mod-http-geoip_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  33794 Sep 13 21:51 libnginx-mod-http-headers-more-filter_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  32984 Sep 13 21:51 libnginx-mod-http-image-filter_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root 166044 Sep 13 21:51 libnginx-mod-http-lua_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  29014 Sep 13 21:51 libnginx-mod-http-ndk_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  40154 Sep 13 21:51 libnginx-mod-http-perl_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  31482 Sep 13 21:51 libnginx-mod-http-subs-filter_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  34958 Sep 13 21:51 libnginx-mod-http-uploadprogress_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  31676 Sep 13 21:51 libnginx-mod-http-upstream-fair_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  31466 Sep 13 21:51 libnginx-mod-http-xslt-filter_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  59964 Sep 13 21:51 libnginx-mod-mail_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root 170052 Sep 13 21:51 libnginx-mod-nchan_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root  80960 Sep 13 21:51 libnginx-mod-stream_1.12.1-0+xenial0_amd64.deb
drwxr-xr-x 10 root root   4096 Sep 13 21:46 nginx-1.12.1
-rw-r--r--  1 root root  24320 Sep 13 21:51 nginx_1.12.1-0+xenial0_all.deb
-rw-r--r--  1 root root  10357 Sep 13 21:51 nginx_1.12.1-0+xenial0_amd64.changes
-rw-r--r--  1 root root 849428 Jul 14 14:28 nginx_1.12.1-0+xenial0.debian.tar.xz
-rw-r--r--  1 root root   4187 Jul 14 14:28 nginx_1.12.1-0+xenial0.dsc
-rw-r--r--  1 root root 981093 Jul 14 14:28 nginx_1.12.1.orig.tar.gz
-rw-r--r--  1 root root  56958 Sep 13 21:51 nginx-common_1.12.1-0+xenial0_all.deb
-rw-r--r--  1 root root  35892 Sep 13 21:51 nginx-doc_1.12.1-0+xenial0_all.deb
-rw-r--r--  1 root root 425094 Sep 13 21:51 nginx-extras_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root 412056 Sep 13 21:51 nginx-full_1.12.1-0+xenial0_amd64.deb
-rw-r--r--  1 root root 389160 Sep 13 21:51 nginx-light_1.12.1-0+xenial0_amd64.deb

Install newly build nginx and dependencies

root@ubuntu:/opt# dpkg --install libnginx-mod-*
Selecting previously unselected package libnginx-mod-http-auth-pam.
(Reading database ... 57824 files and directories currently installed.)
Preparing to unpack libnginx-mod-http-auth-pam_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-auth-pam (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-cache-purge.
Preparing to unpack libnginx-mod-http-cache-purge_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-cache-purge (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-dav-ext.
Preparing to unpack libnginx-mod-http-dav-ext_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-dav-ext (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-echo.
Preparing to unpack libnginx-mod-http-echo_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-echo (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-fancyindex.
Preparing to unpack libnginx-mod-http-fancyindex_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-fancyindex (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-geoip.
Preparing to unpack libnginx-mod-http-geoip_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-geoip (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-headers-more-filter.
Preparing to unpack libnginx-mod-http-headers-more-filter_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-headers-more-filter (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-image-filter.
Preparing to unpack libnginx-mod-http-image-filter_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-image-filter (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-lua.
Preparing to unpack libnginx-mod-http-lua_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-lua (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-ndk.
Preparing to unpack libnginx-mod-http-ndk_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-ndk (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-perl.
Preparing to unpack libnginx-mod-http-perl_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-perl (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-subs-filter.
Preparing to unpack libnginx-mod-http-subs-filter_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-subs-filter (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-uploadprogress.
Preparing to unpack libnginx-mod-http-uploadprogress_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-uploadprogress (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-upstream-fair.
Preparing to unpack libnginx-mod-http-upstream-fair_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-upstream-fair (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-http-xslt-filter.
Preparing to unpack libnginx-mod-http-xslt-filter_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-http-xslt-filter (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-mail.
Preparing to unpack libnginx-mod-mail_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-mail (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-nchan.
Preparing to unpack libnginx-mod-nchan_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-nchan (1.12.1-0+xenial0) ...
Selecting previously unselected package libnginx-mod-stream.
Preparing to unpack libnginx-mod-stream_1.12.1-0+xenial0_amd64.deb ...
Unpacking libnginx-mod-stream (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-auth-pam (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-cache-purge (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-dav-ext (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-echo (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-fancyindex (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-geoip (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-headers-more-filter (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-image-filter (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-ndk (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-perl (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-subs-filter (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-uploadprogress (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-upstream-fair (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-xslt-filter (1.12.1-0+xenial0) ...
Setting up libnginx-mod-mail (1.12.1-0+xenial0) ...
Setting up libnginx-mod-nchan (1.12.1-0+xenial0) ...
Setting up libnginx-mod-stream (1.12.1-0+xenial0) ...
Setting up libnginx-mod-http-lua (1.12.1-0+xenial0) ...

root@ubuntu:/opt# dpkg --install nginx-full_1.12.1-0+xenial0_amd64.deb
(Reading database ... 57921 files and directories currently installed.)
Preparing to unpack nginx-full_1.12.1-0+xenial0_amd64.deb ...
Unpacking nginx-full (1.12.1-0+xenial0) over (1.12.1-0+xenial0) ...
Setting up nginx-full (1.12.1-0+xenial0) ...
Processing triggers for man-db (2.7.5-1) ...

Verify Installation

root@ubuntu:/opt# which nginx

root@ubuntu:/opt# ls /etc/init.d/nginx

root@ubuntu:/opt# nginx -V
nginx version: nginx/1.12.1
built with OpenSSL 1.0.2g  1 Mar 2016
TLS SNI support enabled
configure arguments: --with-cc-opt='-g -O2 -fPIE -fstack-protector-strong -Wformat -Werror=format-security -fPIC -Wdate-time -D_FORTIFY_SOURCE=2' --with-ld-opt='-Wl,-Bsymbolic-functions -fPIE -pie -Wl,-z,relro -Wl,-z,now -fPIC' --prefix=/usr/share/nginx --conf-path=/etc/nginx/nginx.conf --http-log-path=/var/log/nginx/access.log --error-log-path=/var/log/nginx/error.log --lock-path=/var/lock/nginx.lock --pid-path=/run/ --modules-path=/usr/lib/nginx/modules --http-client-body-temp-path=/var/lib/nginx/body --http-fastcgi-temp-path=/var/lib/nginx/fastcgi --http-proxy-temp-path=/var/lib/nginx/proxy --http-scgi-temp-path=/var/lib/nginx/scgi --http-uwsgi-temp-path=/var/lib/nginx/uwsgi --with-debug --with-pcre-jit --with-http_ssl_module --with-http_stub_status_module --with-http_realip_module --with-http_auth_request_module --with-http_v2_module --with-http_dav_module --with-http_slice_module --with-threads --with-http_addition_module --with-http_geoip_module=dynamic --with-http_gunzip_module --with-http_gzip_static_module --with-http_image_filter_module=dynamic --with-http_sub_module --with-http_xslt_module=dynamic --with-stream=dynamic --with-stream_ssl_module --with-stream_ssl_preread_module --with-mail=dynamic --with-mail_ssl_module --add-dynamic-module=/opt/nginx-1.12.1/debian/modules/nginx-auth-pam --add-dynamic-module=/opt/nginx-1.12.1/debian/modules/nginx-dav-ext-module --add-dynamic-module=/opt/nginx-1.12.1/debian/modules/nginx-echo --add-dynamic-module=/opt/nginx-1.12.1/debian/modules/nginx-upstream-fair --add-dynamic-module=/opt/nginx-1.12.1/debian/modules/ngx_http_substitutions_filter_module

Try accessing "http://ipaddress" in browser. You will see following:

Welcome to nginx!

If you see this page, the nginx web server is successfully installed and working. Further configuration is required.
For online documentation and support please refer to
Commercial support is available at
Thank you for using nginx.


Monday, January 30, 2017

Controller Area Network - CAN

Found couple of interesting links on CAN.

What is CAN?

Automative CAN Bus System

Thursday, January 5, 2017

Keycloak - Update user's username

User in Keycloak has a username and email attribute. User's username (used for login) is different from user's email address. In lot of applications user's email address gets used as username. This brings up the usecase where user changes his/her email and the user's username in Keycloak must also be updated.

Keycloak by default doesn't allow admin to update user's username either via UI or API. To update username one need to first enable it at the realm level. Following are the steps:

1. Authenticate as admin

URL: POST https:///auth/realms//protocol/openid-connect/grants/access

2. Get realm

URL: GET https:///auth/admin/realms/

  "id": "bbb4b7eb-ea1e-4ca2-a925-896763cef01a",
  "realm": "",
  "notBefore": 0,
  "accessTokenLifespan": 300,
  "ssoSessionIdleTimeout": 1800,
  "ssoSessionMaxLifespan": 36000,
  "accessCodeLifespan": 60,
  "accessCodeLifespanUserAction": 300,
  "accessCodeLifespanLogin": 1800,
  "enabled": true,
  "sslRequired": "external",
  "registrationAllowed": false,
  "registrationEmailAsUsername": false,
  "rememberMe": false,
  "verifyEmail": false,
  "resetPasswordAllowed": true,
  "editUsernameAllowed": false,
  "userCacheEnabled": true,
  "realmCacheEnabled": true,
  "bruteForceProtected": false,
  "maxFailureWaitSeconds": 900,
  "minimumQuickLoginWaitSeconds": 60,
  "waitIncrementSeconds": 60,
  "quickLoginCheckMilliSeconds": 1000,
  "maxDeltaTimeSeconds": 43200,
  "failureFactor": 30,
  "publicKey": "",
  "certificate": "",
  "requiredCredentials": [
  "otpPolicyType": "totp",
  "otpPolicyAlgorithm": "HmacSHA1",
  "otpPolicyInitialCounter": 0,
  "otpPolicyDigits": 6,
  "otpPolicyLookAheadWindow": 1,
  "otpPolicyPeriod": 30,
  "browserSecurityHeaders": {
    "contentSecurityPolicy": "frame-src 'self'",
    "xFrameOptions": "SAMEORIGIN"
  "smtpServer": {},
  "eventsEnabled": false,
  "eventsListeners": [
  "enabledEventTypes": [],
  "adminEventsEnabled": false,
  "adminEventsDetailsEnabled": false,
  "identityFederationEnabled": false,
  "internationalizationEnabled": false,
  "supportedLocales": [],
  "browserFlow": "browser",
  "registrationFlow": "registration",
  "directGrantFlow": "direct grant",
  "resetCredentialsFlow": "reset credentials",
  "clientAuthenticationFlow": "clients"

3. Update realm to allow updating username

URL: PUT https:///auth/admin/realms/

 "editUsernameAllowed": true,

4. Get user

URL: GET https:///auth/admin/realms//users/a552d630-a696-43ea-9c56-9fe132e5a9a4

  "id": "a552d630-a696-43ea-9c56-9fe132e5a9a4",
  "createdTimestamp": 1483624857856,
  "username": "test",
  "enabled": true,
  "totp": false,
  "emailVerified": true,
  "requiredActions": []

5. Update user's username

URL: https:///auth/admin/realms//users/a552d630-a696-43ea-9c56-9fe132e5a9a4

"username": "test1",
"enabled": true,
"emailVerified": true

note: Keycloak 1.5.0 updates the enabled and emailVerified attributes to false upon update when not explicitly passed. I haven't checked if there are other such attributes.

6. Get user

URL: GET https:///auth/admin/realms//users/a552d630-a696-43ea-9c56-9fe132e5a9a4

  "id": "a552d630-a696-43ea-9c56-9fe132e5a9a4",
  "createdTimestamp": 1483624857856,
  "username": "test1",
  "enabled": true,
  "totp": false,
  "emailVerified": true,
  "requiredActions": []

7. Validate by performing login with username test1 and password.

Feel free to leave comment.

Monday, June 27, 2016

git flow with bamboo and docker

git flow is well known branching model for git repositories. The challenge however is how to make it work when it comes to integrating with build, release and deployment process. This post describes one simple recipe to implement E2E process. The gist of the recipe is to use software version of the package as the docker image tag.

Git flow branching model

git flow branching model is the original post that describes the branching model in detail. I found this link very useful that provides good summary of the git flow with commands for implementing the branching model.

If you are using atlassian suite of products then it is best to name branches after JIRA tickets for better integration and traceability.

Bamboo build process

For every repository create 3 plans as following:

CI and CD Plan

This plan builds from develop branch and create docker image with tag as "latest". The bamboo plan can deploy the image automatically to CD environment. In addition, QualDev (QA) team can request deployment in QualDev environment.

Release Plan

This plan builds from master and release*/hotfix* branches. The docker images are created with tag as (npm package version or maven version). The deployment of images from this build are typically on demand.

Feature Plan

This plan builds from feature* branches. This plan doesn't generate any docker image. This is primarily for running unit and integration tests.

Bamboo plan and Docker Image

Following is the sample job in the bamboo plan to create docker image and push to AWS ECR. This is based on a nodejs project. The project source include a build.json file with placeholders for build key and build number. The dockerfile replaces them with the value passed in the build-arg parameters to docker build command. build.json along with npm package version provide complete context of the build currently deployed in a given environment.

# Configure aws
echo $bamboo_AWS_AKEY > 1.txt
echo $bamboo_AWS_SKEY >> 1.txt
echo "" >> 1.txt
echo "" >> 1.txt
aws configure < 1.txt
# Login to AWS ECR
LOGIN_STRING=`aws ecr get-login --region us-east-1`
PACKAGE_VERSION=$(cat package.json | grep version | head -1 | awk -F: '{ print $2 }' | sed 's/[",]//g' | tr -d '[[:space:]]')
# Build and Push docker image
docker build --build-arg BUILD_KEY=$BUILDKEY --build-arg BUILD_NUMBER=$BUILDNUMBER -t $PRODUCT/$COMPONENT:$TAG -f dockerbuild/Dockerfile --no-cache=true .

Following command in dockerfile updates the build.json
# Update build key and number
RUN sed -i -- "s/BUILDKEY/$BUILD_KEY/g; s/BUILDNUMBER/$BUILD_NUMBER/g" ./build.json

Further an API like following can make the information available to internal users about the details of the service running.
    const build = require('./build.json');

      method: 'GET',
      path: '/about',
      config: {
        handler: function (request, reply) {
          var about = {
            "name": process.env.npm_package_name,
            "version": process.env.npm_package_version,
            "buildKey":  build.buildKey,
            "buildNumber": build.buildNumber,
            "config": conf.getProperties()
          return reply(about);

Friday, April 22, 2016

Polymer 1.0 Vulcanize Error

I recently started getting following error when running "gulp" on polymer starter kit:

Starting 'vulcanize'...
ERROR finding /starter-kit/app/elements/bower_components/bower_components/promise-polyfill/Promise.js
ERROR finding /starter-kit/app/elements/bower_components/whenever.js/whenever.js
ERROR finding /starter-kit/app/elements/bower_components/bower_components/bower_components/bower_components/bower_components/web-animations-js/web-animations-next-lite.min.js
ERROR finding starter-kit/app/elements/bower_components/paper-datatable/weakCache.js
ERROR finding starter-kit/app/elements/weakCache.js

I spent multiple hours looking on google but couldn't find a concrete answer. The same code and command works on my collegues machines.

I figured out that one difference between their and my machine was the npm repository. They were using external repo while I was using internal repo.

The Polymer/vulcanize team released 1.14.9 and it had a critical bug ( As soon as they found that, they unpublished 1.14.9 version. However, before they could unpublish, our internal repo had cached it.

To resolve this I had to manually downgrade to 1.14.8 which I did by changing repo path to public npm repo.

Saturday, April 2, 2016

SSL Error - SSL_VERIFY_CERT_CHAIN:certificate verify failed


Recently (last week), we installed new SSL certificate on the Tomcat instances in production. The process involved:

  1. Create a new Java Keystore
  2. Generate a new CSR
  3. Obtain the certificate for our domain along with certificate chain
  4. Import the certificate with the certificate chain in the keystore
  5. Update Tomcat server.xml to point to new keystore
  6. Restart Tomcat process

The Tomcat instance hosts a SOAP WebService. The verification steps involved

  1. Checking the certificate details in multiple browsers
  2. Verifying SOAP API invocation using SOAP-UI tool

The verification was successful and we applied the change in production.


Within few hours couple of customers reported issue that they are not able to access the API. One customer shared the error log:

Caused by: nested fault: SSL protocol error
error:140CF086:SSL routines:SSL_VERIFY_CERT_CHAIN:certificate verify failed
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

The first reaction was that we messed up something in deployment. Without reviewing 
the error and understanding the root cause the decision was to restore the service 
and the change was rolled back. Since the old certificate was valid for few more weeks,
it was a good decision.


Later in the day I analyzed the error and concluded that there was no issue with the 
certificate or the deployment. Following is the new certificate chain when viewed in the 

Following is the old certificate chain when viewed in the browser

While the root CA is same, the intermediate CA changed from "Verisign Class 3 Secure Server CA - G3" to "Symantec Class 3 Secure Server CA - G4". This change happened because the new certificate that we requested was SHA2. Verisign class 3 certificate is SHA1 whereas Symantec class 3 certificate is SHA2. Symantec has issued new intermediate CA certs with after Verisign aquisition in 2010. 

Clients that don't have Symantec class 3 intermediate certificate in their truststore will fail with error SSL_VERIFY_CERT_CHAIN.


To overcome this error, customers must import the intermediate certificate from following link into their truststore:

Following page has instructions for installing certificate on various platforms:


  1. When installing new certificates, notify customers in advance (few weeks). Do this even if the change is limited to just extension of expiry date or domain name change.
  2. Any change in hashing algorithm i.e. SHA1 to SHA2 or SHA2 to SHA3 should be announced well in time to all customers. Different browsers have different timelines when it comes to migrating from SHA1 to SHA2. The biggest risk of such seemingly minor changes is on API integration.
  3. Observe the certificate chain carefully. Just seeing the green page icon in the browser bar is not sufficient. Share the chain with customer if it different from existing certificate chain.

Update - 04/20/2016

I missed one important part in my analysis. I verified the certificate chain using browser but never bothered to look at the chain in the keystore. It turns out the keystore didn't have full certificate chain and that caused clients to fail. If clients had the intermediate certificate in their truststore it would not have mattered. So the fix on our side was to import root CA.

Update - 04/20/2016

Today we went through another issue which was related to SHA1 to SHA2 update. One of the key customers was not prepared and post update they were not able to access out services. The client software was running on a Windows 2003 server that was never patched and was lacking support for SHA2. They were seeing following error while connecting to our service:

The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.

While this key customer was trying to figure out how to patch their system(which is not easy), we put together a workaround solution for them so that they can continue to use the server. Here is what we did:
  1. Asked customer to use non-secure port. Since customer connects to our APIs over VPN it was okay to use non-secure port. However, it was not possible because the URL was hardcoded in the code and nobody knew where the source is or how to build it. So we went to option #2
  2. We setup a new server. 
    1. Installed the required software (which is Java + Tomcat + WAR file)
    2. Created a new self signed SHA1 certificate for the domain
    3. Configured tomcat to use the new keystore and self signed certificate
    4. Shared the certificate with customer to import in their truststore
    5. Asked customer to update the /etc/hosts (or equivalent for Windows) on their machine to point domain name to the IP of this new server. This avoided the need for changing the hardcoded URL in the code.
Following links were esp useful when troubleshooting and recommending solution to customer to patch their Windows 2003 server: