Template for running Go programs on OpenShift v3 (version 1.4 and higher)

It supports:

• Golang dep manager (dep is a prototype dependency management tool) - /example-golang-dep
• glide manager - /example-glide
• godep manager - /example-godep
• govendor manager - /example-govendor
• Traditional go get - /example

Sample data to try golang template

Data	Value
Go	Go v1.9.2
OpenShift	OpenShift Origin v1.5
Git repository	https://github.com/amsokol/openshift-golang-template.git
Context directory	/example-golang-dep
Folder with main.go to build and run	/example-golang-dep/cmd/server

How to

1. Login with Developer account to OpenShift:

# oc login --insecure-skip-tls-verify -u <username> https://openshift.example.com:8443

2. Create new project:

# oc new-project project1

3. Select project1 project:

# oc project project1

4. Create ImageStream:

# oc create -f ./openshift-golang-template.yaml

5. Login to OpenShift console using browser (e.g. https://openshift.example.com:8443) with Developer account

6. Open project1 project

7. Click Add to Project and select Go

8. Select 1.9.2 - latest from drop down list and click Select

9. Set Name to golang1

10. Set Git Repository URL to https://github.com/amsokol/openshift-golang-template.git or click Try It

11. Click advanced options to add additional configuration parameters

12. Set Context Dir to /example-golang-dep (sample project with dep manager support)

13. Add the following environment variables to Build Configuration section:

• GOPROJECT_ROOT=github.com/amsokol/openshift-golang-template/example-golang-dep
• GOPROJECT_CMD=cmd/server

GOPROJECT_ROOT tells builder the root package of go project
GOPROJECT_CMD tells builder the where "main()" function of "main" package to build and run is located (relative to GOPROJECT_ROOT).
Note: ignore GOPROJECT_CMD if "main()" function of "main" package is located in GOPROJECT_ROOT folder.

In example above "main()" function of "main" package is located in `github.com/amsokol/openshift-golang-template/example-golang-dep/cmd/server`.
GOPROJECT_ROOT is set to `github.com/amsokol/openshift-golang-template/example-golang-dep`.
So GOPROJECT_CMD is set to `cmd/server`

14. [Optional] You can easy provide go build arguments. Just add GO_BUILD_ARGS environment variable to Build Configuration section. For example the following value tells go build to print the commands are run and packages are compiled:

GO_BUILD_ARGS=-x -v

Note: please DO NOT override output file name ("-o" argument)!

15. [Optional] You can easy provide command line arguments to your binary. Just add GOPROJECT_CMD_ARGS environment variable to Deployment Configuration section. For example the following value provides --silent and --force arguments the binary:

GOPROJECT_CMD_ARGS=--silent --force

16. [Optional] You can easy provide configuration files to your binary that are copied by the build script to GOPATH\bin (where your binary file is located). Just add GOPROJECT_CMD_CONFIG, GOPROJECT_CMD_CONFIG1, GOPROJECT_CMD_CONFIG2, GOPROJECT_CMD_CONFIG3, etc. environment variables to Build Configuration section. If your configuration files are located in the same project source control repository GOPROJECT_CMD_CONFIGx values should be GOPROJECT_ROOT related path. But you need to know that store configuration files into project repository is BAD PRACTICES (configuration files usually contain credentials, IPs, etc.). It's much more better to inject configuration file from outside (e.g. download from CI server). In this case set GOPROJECT_CMD_CONFIGx by URL value. Build scripts runs curl utility to download configuration files. It supports:

DICT, FILE, FTP, FTPS, Gopher, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, Telnet, TFTP, SSL certificates, proxies, HTTP/2, cookies, user+password authentication (Basic, Plain, Digest, CRAM-MD5, NTLM, Negotiate and Kerberos) and more. Here are some examples:

Provide configuration file is stored into the same source code repository (not recommended for production):
GOPROJECT_CMD_CONFIG=config/settings.yaml

Provide configuration files are stored into the same source code repository (not recommended for production):
GOPROJECT_CMD_CONFIG1=config/db/db.yaml
GOPROJECT_CMD_CONFIG2=config/messaging/broker.json

Download configuration file via HTTPS:
GOPROJECT_CMD_CONFIG=https://config.server.com/myapp/settings.yaml

Download configuration files via HTTPS:
GOPROJECT_CMD_CONFIG1=https://config.server.com/myapp/db/db.yaml
GOPROJECT_CMD_CONFIG2=smb://config.server.com/messaging/broker.json -u "domain\username:passwd"

Notes:

• If you have only one configuration file use GOPROJECT_CMD_CONFIG environment variable. If you have more that one configuration files use GOPROJECT_CMD_CONFIG1, GOPROJECT_CMD_CONFIG2, GOPROJECT_CMD_CONFIG3, etc. environment variables.
• As you see above you can provide not URL only but other curl arguments like credentials. It very important to pass arguments after URL:

Correct:
GOPROJECT_CMD_CONFIG=smb://config.server.com/messaging/broker.json -u "domain\username:passwd"

Wrong:
GOPROJECT_CMD_CONFIG=-u "domain\username:passwd" smb://config.server.com/messaging/broker.json

17. Leave other options with default values and click Create and wait while pod is created

[Optional] How to add health (liveness and readiness) checks

1. Login to OpenShift console using browser (eg https://openshift.example.com:8443) with Developer account

2. Open project1 project

3. Click Applications -> Deployments

4. Click golang1 in the list

5. Select Configuration tab

6. Click Add Health Checks

7. Click Add Readiness Probe

8. Set Path to '/healthz/ready' and leave other options with default values

9. Click Add Liveness Probe

10. Set Path to '/healthz/live' and leave other options with default values

11. Click Save and wait while pod is created

Helper #1 - you can try golang template using S2I:

s2i build https://github.com/amsokol/openshift-golang-template.git amsokol/golang-openshift:1.9.2-1 golang1 -e GOPROJECT_ROOT=github.com/amsokol/openshift-golang-template/example-golang-dep -e GOPROJECT_CMD=cmd/server --context-dir /example-golang-dep

Helper #2 - how to export/edit template from OpenShift

1. Login using oc as OpenShift administrator

2. Run:

# oc get templates -n openshift
# oc edit template -n openshift nodejs-mongo-persistent