fix(generate): keep steps before first stage of base dockerfile

 fixes #350

packages/generate/src/extended-docker-syntax.ts

@@ -29,7 +29,7 @@ async function applyExtendedDockerSyntaxCopy(step: string, pkg: Package): Promis
     const [_, fromStage, chown, ifExistsFlag, slimFlag, filesList, destination] = step.match(isCopy)!;
     if (fromStage) {
         const [_, fromStageName] = fromStage.match(/--from=(\S*)/) ?? [];
-        const isLocalStage = pkg.dockerFile!.find(x => x.originalName === fromStageName);
+        const isLocalStage = pkg.dockerFile!.stages.find(x => x.originalName === fromStageName);
         if (isLocalStage) {
             return `COPY --from=${isLocalStage.name} ${chown || ''} ${filesList} ${destination}`;
         }

packages/generate/src/iterate-dependencies.ts

@@ -3,15 +3,15 @@ import { PackageGraph } from '@lerna/package-graph';
 import { runTopologically } from '@lerna/run-topologically';
 import { IGenerateArgs } from './args';
 import { Package } from './package';
-import { DockerStage } from './read-dockerfile';
+import { Dockerfile } from './read-dockerfile';
 
 export async function iterateDependencies(
     args: IGenerateArgs,
     lernaPackages: lernaPackage[],
     packageGraph: PackageGraph,
     concurrency: number,
     rejectCycles?: boolean,
-    defaultDockerFile?: DockerStage[],
+    defaultDockerFile?: Dockerfile,
 ): Promise<Package[]> {
     const packages: Package[] = [];
     await runTopologically(

packages/generate/src/lerna-command.ts

@@ -32,11 +32,13 @@ export class Dockerize extends Command {
                 defaultDockerFile = await readDockerfile(templateDockerFileName);
             }
 
-            const baseStage = baseDockerFile[baseDockerFile.length - 1];
+            const baseStage = baseDockerFile.stages[baseDockerFile.stages.length - 1];
             baseStage.name = 'base';
 
-            const result: string[] = [];
-            for (let baseStage of baseDockerFile) {
+            const result: string[] = [
+                ...baseDockerFile.preStage,
+            ];
+            for (let baseStage of baseDockerFile.stages) {
                 result.push(getDockerFileFromInstruction(baseStage.baseImage, baseStage.name, baseStage.platform));
                 result.push(...baseStage.stepsBeforeInstall);
                 if (baseStage.install) {
@@ -93,7 +95,7 @@ export class Dockerize extends Command {
 
         // overwrite final docker stage
         if (finalDockerfileName) {
-            finalStages = await readDockerfile(finalDockerfileName);
+            finalStages = (await readDockerfile(finalDockerfileName)).stages;
         }
 
         for (let finalStage of finalStages) {

packages/generate/src/package.ts

@@ -1,6 +1,6 @@
 import { PackageGraphNode } from '@lerna/package-graph';
 import { Package as LernaPackage } from '@lerna/package';
-import { DockerStage, readDockerfile } from './read-dockerfile';
+import { Dockerfile, DockerStage, readDockerfile } from './read-dockerfile';
 import { promises } from 'fs';
 import { join as joinPath, relative } from 'path';
 import { getDependenciesTransitive } from './get-dependencies-transitive';
@@ -15,7 +15,7 @@ export type PackageMap = Map<string, Package>;
 
 export class Package {
 
-    dockerFile?: DockerStage[];
+    dockerFile?: Dockerfile;
 
     constructor(
         public name: string,
@@ -46,7 +46,7 @@ export class Package {
         return undefined;
     }
 
-    async loadDockerfile(defaultDockerFile?: DockerStage[]): Promise<DockerStage[]> {
+    async loadDockerfile(defaultDockerFile?: Dockerfile): Promise<Dockerfile> {
         const dockerFileName = await this.findDockerfile();
         if (!dockerFileName && !defaultDockerFile) {
             throw new Error(`No Dockerfile for the package ${this.name} and no default docker file was found!`);
@@ -58,7 +58,10 @@ export class Package {
             getLogger().info(`using custom dockerfile for package ${this.name}`);
             this.dockerFile = await readDockerfile(dockerFileName);
         }
-        this.dockerFile = this.dockerFile!.map((stage, i) => this.scopeDockerStage(stage, i));
+        this.dockerFile = {
+            stages: this.dockerFile!.stages.map((stage, i) => this.scopeDockerStage(stage, i)),
+            preStage: this.dockerFile!.preStage,
+        };
         return this.dockerFile!;
     }
 
@@ -76,7 +79,7 @@ export class Package {
         if (!this.args.addPrepareStages) {
             return this.getBuildStageName();
         }
-        return this.dockerFile[this.dockerFile.length - 1].prepareStageName;
+        return this.dockerFile.stages[this.dockerFile.stages.length - 1].prepareStageName;
     }
 
     getBuildStageName(): string | undefined {
@@ -87,7 +90,7 @@ export class Package {
         if (!this.dockerFile) {
             return undefined;
         }
-        return this.dockerFile[this.dockerFile.length - 1];
+        return this.dockerFile.stages[this.dockerFile.stages.length - 1];
     }
 
     stageHasInstall(stage?: DockerStage): boolean {
@@ -102,9 +105,9 @@ export class Package {
             return [];
         }
         const result: string[] = [];
-        for (let stage of this.dockerFile) {
+        for (let stage of this.dockerFile.stages) {
             let baseImage = stage.baseImage;
-            const baseImageIsLocalStage = this.dockerFile!.find(x => x.originalName === baseImage);
+            const baseImageIsLocalStage = this.dockerFile!.stages.find(x => x.originalName === baseImage);
             if (baseImageIsLocalStage) {
                 baseImage = baseImageIsLocalStage.name!;
             }

packages/generate/src/read-dockerfile.ts

@@ -19,32 +19,45 @@ export interface DockerStage {
     install?: IInstallOptions;
 }
 
+export interface Dockerfile {
+    stages: DockerStage[];
+    preStage: string[];
+}
+
 
-export async function readDockerfile(path: string): Promise<DockerStage[]> {
+export async function readDockerfile(path: string): Promise<Dockerfile> {
     const dockerfile = (await promises.readFile(path)).toString();
     const steps = splitInSteps(dockerfile);
     const result = [];
     let currentStep = 0;
+    let preStage: string[] = [];
     while (true) {
         const readStageResult = readStage(steps, currentStep);
         if (!readStageResult) {
             break;
         }
         currentStep = readStageResult.endIndex + 1;
         result.push(readStageResult.stage);
+        if (preStage.length === 0 && readStageResult.preStage.length > 0) {
+            preStage = readStageResult.preStage;
+        }
     }
     if (result.length === 0) {
         getLogger().warn(`The dockerfile '${path}' appears to be empty.`);
     }
-    return result;
+    return {
+        preStage: preStage,
+        stages: result,
+    };
 }
 
-export function readStage(steps: string[], startIndex: number): { stage: DockerStage; endIndex: number } | undefined {
+export function readStage(steps: string[], startIndex: number): { stage: DockerStage; endIndex: number; preStage: string[] } | undefined {
     let i = startIndex;
     let baseImage;
     let stageName;
     let platform;
-    const isStageFromClause = /(FROM|from)(\s--platform=(\S+))? ([a-zA-Z0-9:_\-@.\/]*)( as ([a-zA-Z0-9:_-]*))?/;
+    const preStage = [];
+    const isStageFromClause = /(FROM|from)(\s--platform=(\S+))? ([a-zA-Z0-9:_\-@.\/${}]*)( as ([a-zA-Z0-9:_-]*))?/;
     for (; ; i++) {
         if (i >= steps.length) {
             return undefined;
@@ -57,6 +70,7 @@ export function readStage(steps: string[], startIndex: number): { stage: DockerS
             i++;
             break;
         }
+        preStage.push(steps[i]);
     }
     const stepsBeforeInstall: string[] = [];
     const stepsAfterInstall: string[] = [];
@@ -93,6 +107,7 @@ export function readStage(steps: string[], startIndex: number): { stage: DockerS
             stepsAfterInstall,
             install: installHit,
         },
+        preStage,
     };
 }