Scheduling Posts with GitOps, Durable Functions and GitHub Actions

01-payload-ac.json

{
  "owner": "aliencube",
  "repository": "blog",
  "issueId": 3,
  "schedule": "2020-03-25T07:00:00+09:00"
}

01-payload-dk.json

{
  "owner": "devkimchi",
  "repository": "blog",
  "issueId": 3,
  "schedule": "2020-03-25T07:00:00+09:00"
}

02-entrypoint.cs

[FunctionName("SetSchedule")]
public async Task<HttpResponseMessage> SetSchedule(
    [HttpTrigger(AuthorizationLevel.Function, "post", Route = "orchestrators/{orchestratorName}")] HttpRequestMessage req,
    [DurableClient] IDurableOrchestrationClient starter,
    string orchestratorName,
    ILogger log)
{
    var input = await req.Content.ReadAsAsync<EventSchedulingRequest>();
    var instanceId = await starter.StartNewAsync<EventSchedulingRequest>(orchestratorName, instanceId: null, input: input);

    log.LogInformation($"Started orchestration with ID = '{instanceId}'.");

    return starter.CreateCheckStatusResponse(req, instanceId);
}

03-orchestrator.cs

[FunctionName("schedule-event")]
public async Task<object> RunOrchestrator(
    [OrchestrationTrigger] IDurableOrchestrationContext context,
    ILogger log)
{
    var input = context.GetInput<EventSchedulingRequest>();

    // Set the maximum duration. Max duration can't exceed 7 days.
    var maxDuration = TimeSpan.Parse(Environment.GetEnvironmentVariable("Duration__Max"), CultureInfo.InvariantCulture);
    if (maxDuration > threshold)
    {
        return "Now allowed";
    }

    // Get the scheduled time
    var scheduled = input.Schedule.UtcDateTime;

    // Get the function initiated time.
    var initiated = context.CurrentUtcDateTime;

    // Get the difference between now and schedule
    var datediff = (TimeSpan)(scheduled - initiated);

    // Complete if datediff is longer than the max duration
    if (datediff >= maxDuration)
    {
        return "Too far away";
    }

    await context.CreateTimer(scheduled, CancellationToken.None);

    var output = await context.CallActivityAsync<object>("CallRepositoryDispatchEvent", input);

    return output;
}

04-activity.cs

[FunctionName("CallMergePrRepositoryDispatchEvent")]
public async Task<object> MergePr(
    [ActivityTrigger] EventSchedulingRequest input,
    ILogger log)
{
    var authKey = Environment.GetEnvironmentVariable("GitHub__AuthKey");
    var requestUri = $"{Environment.GetEnvironmentVariable("GitHub__BaseUri").TrimEnd('/')}/repos/{input.Owner}/{input.Repository}/{Environment.GetEnvironmentVariable("GitHub__Endpoints__Dispatches").TrimStart('/')}";
    var accept = Environment.GetEnvironmentVariable("GitHub__Headers__Accept");
    var userAgent = Environment.GetEnvironmentVariable("GitHub__Headers__UserAgent");

    this._client.DefaultRequestHeaders.Clear();
    this._client.DefaultRequestHeaders.Add("Authorization", authKey);
    this._client.DefaultRequestHeaders.Add("Accept", accept);
    this._client.DefaultRequestHeaders.Add("User-Agent", userAgent);

    var payload = new RepositoryDispatchEventRequest<EventSchedulingRequest>("merge-pr", input);

    using (var content = new ObjectContent<RepositoryDispatchEventRequest<EventSchedulingRequest>>(payload, this._formatter, "application/json"))
    using (var response = await this._client.PostAsync(requestUri, content).ConfigureAwait(false))
    {
        response.EnsureSuccessStatusCode();
    }

    return payload;
}

05-webhook.cs

[FunctionName("CallPublishRepositoryDispatchEvent")]
public async Task<IActionResult> Publish(
    [HttpTrigger(AuthorizationLevel.Function, "post", Route = "events/publish")] HttpRequest req,
    ILogger log)
{
    var input = JsonConvert.DeserializeObject<EventRequest>(await new StreamReader(req.Body).ReadToEndAsync());

    var authKey = Environment.GetEnvironmentVariable("GitHub__AuthKey");
    var requestUri = $"{Environment.GetEnvironmentVariable("GitHub__BaseUri").TrimEnd('/')}/repos/{input.Owner}/{input.Repository}/{Environment.GetEnvironmentVariable("GitHub__Endpoints__Dispatches").TrimStart('/')}";
    var accept = Environment.GetEnvironmentVariable("GitHub__Headers__Accept");
    var userAgent = Environment.GetEnvironmentVariable("GitHub__Headers__UserAgent");

    this._client.DefaultRequestHeaders.Clear();
    this._client.DefaultRequestHeaders.Add("Authorization", authKey);
    this._client.DefaultRequestHeaders.Add("Accept", accept);
    this._client.DefaultRequestHeaders.Add("User-Agent", userAgent);

    var payload = new RepositoryDispatchEventRequest<EventSchedulingRequest>("publish", input);

    using (var content = new ObjectContent<RepositoryDispatchEventRequest<EventSchedulingRequest>>(payload, this._formatter, "application/json"))
    using (var response = await this._client.PostAsync(requestUri, content).ConfigureAwait(false))
    {
        response.EnsureSuccessStatusCode();
    }

    return payload;
}

06-workflow.yaml

name: Merge PR

on: repository_dispatch

jobs:
  merge_pr:
    name: Merge PR
    if: github.event.action == 'merge-pr'

    runs-on: ubuntu-latest

    steps:
    - name: Merge PR
      uses: justinyoo/github-pr-merge-action@v0.8.0
      with:
        authToken: ${{ secrets.GITHUB_TOKEN }}
        owner: ${{ github.event.client_payload.owner }}
        repository:  ${{ github.event.client_payload.repository }}
        issueId: '${{ github.event.client_payload.issueId }}'
        mergeMethod: Squash
        commitTitle: ''
        commitDescription: ''
        deleteBranch: 'true'
    - name: Send dispatch event for publish
      shell: bash
      run: |
        curl -X POST 'https://${{ secrets.AZURE_FUNCTIONS_NAME }}.azurewebsites.net/api/events/publish' -d '{ "owner": "${{ secrets.OWNER }}", "repository": "${{ secrets.REPOSITORY }}" }' -H "x-functions-key: ${{ secrets.AZURE_FUNCTIONS_KEY }}" -H "Content-Type: application/json"

  build_and_publish:
    name: Build and publish
    if: github.event.action == 'publish'

    runs-on: ubuntu-latest

    steps:
      ...