From 4c25474726b259a9886b8ecb19364a9ce8dad4d3 Mon Sep 17 00:00:00 2001
From: Justin Roberson <justin.roberson@tackle.io>
Date: Fri, 10 Dec 2021 11:31:54 -0500
Subject: [PATCH] fix: fallback to default TF version in apply step

The plan step has a mechanism to use the default tf version from the Terraform
client if the context does not define one, however the apply step does not have
this. This results in remote executions of apply failing with a nil pointer
dereference when it checks tfVersion in StripRefreshingFromPlanOutput. This fix
involves copying what the PlanStepRunner does and falls back to the default
version if the context's version is nil.
---
 server/core/runtime/apply_step_runner.go | 10 ++++++++--
 server/server.go                         |  1 +
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/server/core/runtime/apply_step_runner.go b/server/core/runtime/apply_step_runner.go
index d4bcd90c69..0f9d5458d8 100644
--- a/server/core/runtime/apply_step_runner.go
+++ b/server/core/runtime/apply_step_runner.go
@@ -16,11 +16,17 @@ import (
 // ApplyStepRunner runs `terraform apply`.
 type ApplyStepRunner struct {
 	TerraformExecutor   TerraformExec
+	DefaultTFVersion    *version.Version
 	CommitStatusUpdater StatusUpdater
 	AsyncTFExec         AsyncTFExec
 }
 
 func (a *ApplyStepRunner) Run(ctx models.ProjectCommandContext, extraArgs []string, path string, envs map[string]string) (string, error) {
+	tfVersion := a.DefaultTFVersion
+	if ctx.TerraformVersion != nil {
+		tfVersion = ctx.TerraformVersion
+	}
+
 	if a.hasTargetFlag(ctx, extraArgs) {
 		return "", errors.New("cannot run apply with -target because we are applying an already generated plan. Instead, run -target with atlantis plan")
 	}
@@ -40,7 +46,7 @@ func (a *ApplyStepRunner) Run(ctx models.ProjectCommandContext, extraArgs []stri
 	// TODO: Leverage PlanTypeStepRunnerDelegate here
 	if IsRemotePlan(contents) {
 		args := append(append([]string{"apply", "-input=false", "-no-color"}, extraArgs...), ctx.EscapedCommentArgs...)
-		out, err = a.runRemoteApply(ctx, args, path, planPath, ctx.TerraformVersion, envs)
+		out, err = a.runRemoteApply(ctx, args, path, planPath, tfVersion, envs)
 		if err == nil {
 			out = a.cleanRemoteApplyOutput(out)
 		}
@@ -48,7 +54,7 @@ func (a *ApplyStepRunner) Run(ctx models.ProjectCommandContext, extraArgs []stri
 		// NOTE: we need to quote the plan path because Bitbucket Server can
 		// have spaces in its repo owner names which is part of the path.
 		args := append(append(append([]string{"apply", "-input=false", "-no-color"}, extraArgs...), ctx.EscapedCommentArgs...), fmt.Sprintf("%q", planPath))
-		out, err = a.TerraformExecutor.RunCommandWithVersion(ctx.Log, path, args, envs, ctx.TerraformVersion, ctx.Workspace)
+		out, err = a.TerraformExecutor.RunCommandWithVersion(ctx.Log, path, args, envs, tfVersion, ctx.Workspace)
 	}
 
 	// If the apply was successful, delete the plan.
diff --git a/server/server.go b/server/server.go
index 94ce797039..7d1e6af36b 100644
--- a/server/server.go
+++ b/server/server.go
@@ -487,6 +487,7 @@ func NewServer(userConfig UserConfig, config Config) (*Server, error) {
 		PolicyCheckStepRunner: policyCheckRunner,
 		ApplyStepRunner: &runtime.ApplyStepRunner{
 			TerraformExecutor:   terraformClient,
+			DefaultTFVersion:    defaultTfVersion,
 			CommitStatusUpdater: commitStatusUpdater,
 			AsyncTFExec:         terraformClient,
 		},