feat: propagate proxy variables to jobs, services and builds (#1112)

Set `http_proxy`, `https_proxy` and `no_proxy` in the runner's environment and everything the runner controls uses them.

Go already read them for the runner's own requests. This adds jobs, in lower and upper case, service containers, and Dockerfile action builds.

Some hosts are added to `no_proxy` for jobs so they stay direct: the cache server, loopback, the job's service containers, and a `tcp://` Docker daemon. Without the last one the Docker client sends its API calls to the proxy and docker-in-docker breaks. Gitea is not added.

Images are pulled by the Docker daemon, which has its own proxy setting. In the `dind` images it reads these same variables. The runner warns at startup if it has a proxy and the daemon does not.

Fixes https://gitea.com/gitea/runner/issues/1118, originally reported as https://gitea.com/gitea/runner/issues/708.

---------

Co-authored-by: silverwind <2021+silverwind@noreply.gitea.com>
Co-authored-by: silverwind <me@silverwind.io>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1112
Reviewed-by: silverwind <2021+silverwind@noreply.gitea.com>
Co-authored-by: bircni <bircni@icloud.com>

act/runner/run_context_test.go

@@ -292,6 +292,83 @@ jobs:
 	require.Equal(t, [2]string{"", ""}, credentials["redis:latest"])
 }
 
+// A service container reaches the internet the same way the job does, so it inherits the
+// job's proxy; a service that sets the variable itself keeps its own value.
+func TestStartJobContainerGivesServicesTheJobProxy(t *testing.T) {
+	workflow, err := model.ReadWorkflow(strings.NewReader(`
+name: test
+on: push
+jobs:
+  job:
+    runs-on: ubuntu-latest
+    container:
+      image: registry.example/job:latest
+    services:
+      redis:
+        image: redis:latest
+      db:
+        image: postgres:latest
+        env:
+          no_proxy: db-only.example
+    steps: []
+`))
+	require.NoError(t, err)
+
+	var inputs []*container.NewContainerInput
+	origNewContainer := newContainer
+	newContainer = func(input *container.NewContainerInput) container.ExecutionsEnvironment {
+		inputs = append(inputs, input)
+		return fakeContainer{}
+	}
+	t.Cleanup(func() { newContainer = origNewContainer })
+
+	rc := &RunContext{
+		Name: "test",
+		Config: &Config{
+			Workdir:              "/tmp",
+			ContainerNetworkMode: "host",
+			ReuseContainers:      true,
+			Env:                  map[string]string{},
+			ProxyEnv:             map[string]string{"http_proxy": "http://proxy:3128", "no_proxy": "internal.example"},
+			Secrets:              map[string]string{},
+		},
+		Env: map[string]string{},
+		Run: &model.Run{
+			JobID:    "job",
+			Workflow: workflow,
+		},
+	}
+	rc.ExprEval = rc.NewExpressionEvaluator(t.Context())
+
+	require.NoError(t, rc.startJobContainer()(t.Context()))
+
+	env := map[string][]string{}
+	for _, in := range inputs {
+		env[in.Image] = in.Env
+	}
+
+	require.Contains(t, env["redis:latest"], "http_proxy=http://proxy:3128")
+	require.Contains(t, env["redis:latest"], "no_proxy=internal.example")
+	// the service's own env wins over what the runner injected, without dropping the rest
+	require.Contains(t, env["postgres:latest"], "no_proxy=db-only.example")
+	require.NotContains(t, env["postgres:latest"], "no_proxy=internal.example")
+	require.Contains(t, env["postgres:latest"], "http_proxy=http://proxy:3128")
+}
+
+// act builds Dockerfile actions through the API, which does not pre-populate the proxy
+// build args the docker CLI would, so the RUN steps would have no network behind a proxy.
+func TestProxyBuildArgs(t *testing.T) {
+	rc := &RunContext{Config: &Config{ProxyEnv: map[string]string{"http_proxy": "http://proxy:3128"}}}
+
+	args := rc.proxyBuildArgs()
+
+	require.Len(t, args, 1)
+	require.Equal(t, "http://proxy:3128", *args["http_proxy"])
+
+	// a job without a proxy builds exactly as it does today
+	require.Nil(t, (&RunContext{Config: &Config{}}).proxyBuildArgs())
+}
+
 func TestRunContext_GetBindsAndMounts(t *testing.T) {
 	rctemplate := &RunContext{
 		Name: "TestRCName",