Jenkinsfile: run each py.test on a separate executor

Running all py.test processes in parallel on the same executor is not a good idea.
If a node has not much RAM, it could run out of memory when all py.test processes
run at the same time. And If there are only 2 CPU cores, it doesn't make sense
to run more then 2 processes either.
Therefore use a separate executor for each one. The py.test processes will thus
only run in parallel if there are multiple Jenkins executors available.

Jenkinsfile

@@ -1,166 +1,181 b''
+def createvirtualenv = ''
+def activatevirtualenv = ''
+
 node {
-    def createvirtualenv = ''
-    def activatevirtualenv = ''
     if (isUnix()) {
         createvirtualenv = 'rm -r $JENKINS_HOME/venv/$JOB_NAME || true && virtualenv $JENKINS_HOME/venv/$JOB_NAME'
         activatevirtualenv = '. $JENKINS_HOME/venv/$JOB_NAME/bin/activate'
     } else {
         createvirtualenv = 'rmdir /s /q %JENKINS_HOME%\\venv\\%JOB_NAME% || true && virtualenv %JENKINS_HOME%\\venv\\%JOB_NAME%'
         activatevirtualenv = 'call %JENKINS_HOME%\\venv\\%JOB_NAME%\\Scripts\\activate.bat'
     }
 
     stage('checkout') {
         checkout scm
         if (isUnix()) {
             sh 'hg --config extensions.purge= purge --all'
         } else {
             bat 'hg --config extensions.purge= purge --all'
         }
     }
     stage('virtual env') {
         def virtualenvscript = """$createvirtualenv
             $activatevirtualenv
             python -m pip install --upgrade pip
             pip install --upgrade setuptools
             pip install --upgrade pylint
             pip install --upgrade pytest-cov
             """
         if (isUnix()) {
             virtualenvscript += """
                 pip install --upgrade python-ldap
                 pip install --upgrade python-pam
                 """
             sh virtualenvscript
         } else {
             bat virtualenvscript
         }
     }
     stage('setup') {
         def virtualenvscript = """$activatevirtualenv
             pip install --upgrade -e .
             pip install -r dev_requirements.txt
             python setup.py compile_catalog
             """
         if (isUnix()) {
             sh virtualenvscript
         } else {
             bat virtualenvscript
         }
         stash name: 'kallithea', useDefaultExcludes: false
     }
     stage('pylint') {
         sh script: """$activatevirtualenv
             pylint -j 0 --disable=C -f parseable kallithea > pylint.out
             """, returnStatus: true
         archiveArtifacts 'pylint.out'
         try {
             step([$class: 'WarningsPublisher', canComputeNew: false, canResolveRelativePaths: false, defaultEncoding: '', excludePattern: '', healthy: '', includePattern: '', messagesPattern: '', parserConfigurations: [[parserName: 'PyLint', pattern: 'pylint.out']], unHealthy: ''])
         } catch (java.lang.IllegalArgumentException exc) {
             echo "You need to install the 'Warnings Plug-in' to display the pylint report."
             currentBuild.result = 'UNSTABLE'
             echo "Caught: ${exc}"
         }
     }
-    def pytests = [:]
-    pytests['sqlite'] = {
+}
+
+def pytests = [:]
+pytests['sqlite'] = {
+    node {
         ws {
             deleteDir()
             unstash name: 'kallithea'
             if (isUnix()) {
                 sh script: """$activatevirtualenv
                     py.test -p no:sugar --cov-config .coveragerc --junit-xml=pytest_sqlite.xml --cov=kallithea --cov-report xml
                     """, returnStatus: true
             } else {
                 bat script: """$activatevirtualenv
                     py.test -p no:sugar --cov-config .coveragerc --junit-xml=pytest_sqlite.xml --cov=kallithea --cov-report xml
                     """, returnStatus: true
             }
             sh 'sed --in-place "s/\\(classname=[\'\\"]\\)/\\1SQLITE./g" pytest_sqlite.xml'
             archiveArtifacts 'pytest_sqlite.xml'
             junit 'pytest_sqlite.xml'
             try {
                 step([$class: 'CoberturaPublisher', autoUpdateHealth: false, autoUpdateStability: false, coberturaReportFile: 'coverage.xml', failNoReports: false, failUnhealthy: false, failUnstable: false, maxNumberOfBuilds: 0, onlyStable: false, zoomCoverageChart: false])
             } catch (java.lang.IllegalArgumentException exc) {
                 echo "You need to install the pipeline compatible 'CoberturaPublisher Plug-in' to display the coverage report."
                 currentBuild.result = 'UNSTABLE'
                 echo "Caught: ${exc}"
             }
         }
     }
-    if (isUnix()) {
-        pytests['de'] = {
+}
+
+pytests['de'] = {
+    node {
+        if (isUnix()) {
             ws {
                 deleteDir()
                 unstash name: 'kallithea'
                 withEnv(['LANG=de_DE.UTF-8',
                     'LANGUAGE=de',
                     'LC_ADDRESS=de_DE.UTF-8',
                     'LC_IDENTIFICATION=de_DE.UTF-8',
                     'LC_MEASUREMENT=de_DE.UTF-8',
                     'LC_MONETARY=de_DE.UTF-8',
                     'LC_NAME=de_DE.UTF-8',
                     'LC_NUMERIC=de_DE.UTF-8',
                     'LC_PAPER=de_DE.UTF-8',
                     'LC_TELEPHONE=de_DE.UTF-8',
                     'LC_TIME=de_DE.UTF-8',
                 ]) {
                     sh script: """$activatevirtualenv
                         py.test -p no:sugar --cov-config .coveragerc --junit-xml=pytest_de.xml --cov=kallithea --cov-report xml
                         """, returnStatus: true
                 }
                 sh 'sed --in-place "s/\\(classname=[\'\\"]\\)/\\1DE./g" pytest_de.xml'
                 archiveArtifacts 'pytest_de.xml'
                 junit 'pytest_de.xml'
             }
         }
-        pytests['mysql'] = {
+    }
+}
+pytests['mysql'] = {
+    node {
+        if (isUnix()) {
             ws {
                 deleteDir()
                 unstash name: 'kallithea'
                 sh """$activatevirtualenv
                     pip install --upgrade MySQL-python
                     """
                 withEnv(['TEST_DB=mysql://kallithea:kallithea@jenkins_mysql/kallithea_test?charset=utf8']) {
                     if (isUnix()) {
                         sh script: """$activatevirtualenv
                             py.test -p no:sugar --cov-config .coveragerc --junit-xml=pytest_mysql.xml --cov=kallithea --cov-report xml
                             """, returnStatus: true
                     } else {
                         bat script: """$activatevirtualenv
                             py.test -p no:sugar --cov-config .coveragerc --junit-xml=pytest_mysql.xml --cov=kallithea --cov-report xml
                             """, returnStatus: true
                     }
                 }
                 sh 'sed --in-place "s/\\(classname=[\'\\"]\\)/\\1MYSQL./g" pytest_mysql.xml'
                 archiveArtifacts 'pytest_mysql.xml'
                 junit 'pytest_mysql.xml'
             }
         }
-        pytests['postgresql'] = {
+    }
+}
+pytests['postgresql'] = {
+    node {
+        if (isUnix()) {
             ws {
                 deleteDir()
                 unstash name: 'kallithea'
                 sh """$activatevirtualenv
                     pip install --upgrade psycopg2
                     """
                 withEnv(['TEST_DB=postgresql://kallithea:kallithea@jenkins_postgresql/kallithea_test']) {
                     if (isUnix()) {
                         sh script: """$activatevirtualenv
                             py.test -p no:sugar --cov-config .coveragerc --junit-xml=pytest_postgresql.xml --cov=kallithea --cov-report xml
                             """, returnStatus: true
                     } else {
                         bat script: """$activatevirtualenv
                             py.test -p no:sugar --cov-config .coveragerc --junit-xml=pytest_postgresql.xml --cov=kallithea --cov-report xml
                             """, returnStatus: true
                     }
                 }
                 sh 'sed --in-place "s/\\(classname=[\'\\"]\\)/\\1POSTGRES./g" pytest_postgresql.xml'
                 archiveArtifacts 'pytest_postgresql.xml'
                 junit 'pytest_postgresql.xml'
             }
         }
     }
-    stage('Tests') {
-        parallel pytests
-    }
 }
+stage('Tests') {
+    parallel pytests
+}