I have been exploring Google Cloud Build recently and this post is a simple introduction to this product. You can think of it as a tool that enables automation of deployments. This post though will not go as far as automating deployments, instead just covering the basics of what it involves in getting a pipeline going. A follow up post will show a continuous deployment pipeline for a java application.
Steps
The basic steps to set-up a Cloud Build in your GCP project is explained here. Assuming that the Cloud Build has been set-up, I will be using this github project to create a pipeline.
Cloud pipeline is typically placed as a yaml configuration in a file named by convention as “cloudbuild.yaml”. The pipeline is described as a series of steps, each step runs in a docker container and the name of the step points to the docker image. So for eg. a step which echo’s a message looks like this:
steps:
- name: 'bash'
id: hello
args: ['echo', 'Hello World']
Here the name “bash” points to the docker image named “bash” in docker hub
The project does not need to be configured in Google Cloud Build to run it, instead a utility called
“cloud-build-local” can be used for running the build file.
git clone git@github.com:bijukunjummen/hello-cloud-build.git cd hello-cloud-build cloud-build-local .
Alright, now to add a few more steps. Consider a build file with 2 steps:
steps:
- name: 'bash'
id: A
args: ['echo', 'Step A']
- name: 'bash'
id: B
args: ['echo', 'Step B']
Here the two steps will run serially, first Step A, then Step B. A sample output looks like this on my machine:
Starting Step #0 - "A" Step #0 - "A": Already have image (with digest): bash Step #0 - "A": Step A Finished Step #0 - "A" 2021/08/10 12:50:23 Step Step #0 - "A" finished Starting Step #1 - "B" Step #1 - "B": Already have image (with digest): bash Step #1 - "B": Step B Finished Step #1 - "B" 2021/08/10 12:50:25 Step Step #1 - "B" finished 2021/08/10 12:50:26 status changed to "DONE"
Concurrent Steps
A little more complex, say if I wanted to execute a few steps concurrently, the way to do it is using waitFor property of a step.
steps:
- name: 'bash'
id: A
args: ['echo', 'Step A']
waitFor:
- "-"
- name: 'bash'
id: B
args: ['echo', 'Step B']
waitFor:
- "-"
Here “waitFor” value of “-” indicates the start of the build, so essentially Step A and B will run concurrently and an output in my machine looks like this:
Starting Step #1 - "B" Starting Step #0 - "A" Step #1 - "B": Already have image (with digest): bash Step #0 - "A": Already have image (with digest): bash Step #1 - "B": Step B Step #0 - "A": Step A Finished Step #1 - "B" 2021/08/10 12:54:21 Step Step #1 - "B" finished Finished Step #0 - "A" 2021/08/10 12:54:21 Step Step #0 - "A" finished
One more example where Step A is executed first and then Step B and Step C concurrently:
steps:
- name: 'bash'
id: A
args: ['echo', 'Step A']
- name: 'bash'
id: B
args: ['echo', 'Step B']
waitFor:
- "A"
- name: 'bash'
id: C
args: ['echo', 'Step C']
waitFor:
- "A"
Passing Data
A root volume at path “/workspace” carries through the build, so if a step wants to pass data to another step then it can be passed through this “/workspace” folder.
steps:
- name: 'bash'
id: A
entrypoint: bash
args:
- -c
- |
echo "hello" > /workspace/saved.txt
- name: 'bash'
id: B
entrypoint: bash
args:
- -c
- |
cat /workspace/saved.txt
Here Step A is writing to a file and Step B is reading from the same file.
Conclusion
This covers the basics of the steps in a Cloud Build configuration file. In a subsequent post I will be using these to create a pipeline to deploy a java based application to
Google Cloud Run.
Published on Java Code Geeks with permission by Biju Kunjummen, partner at our JCG program. See the original article here: Google Cloud Build – Hello World Opinions expressed by Java Code Geeks contributors are their own. |
