fix: switch to python3 (#11)

closes #7 
fix: skip idempodence test on compact

.travis.yml

@@ -1,19 +1,17 @@
 ---
-services:
-  - docker
+os: linux
+dist: bionic
 language: python
-python: "2.7"
 cache: pip
-
-sudo: required
-dist: xenial
+services:
+  - docker
 
 env:
   global:
     - GREEN='\033[0;32m'
     - RED='\033[0;31m'
     - NC='\033[0m' # No Color
-  matrix:
+  jobs:
     - TEST=basic db_name=telegraf rp_name=rp_4d
     - TEST=setup db_name=telegraf_30d rp_name=rp_30d
     - TEST=migrate db_name=test_4d rp_name=rp_4d db_name_source=test
@@ -40,7 +38,7 @@ install:
     fi
 
   # Install ansible and jq.
-  - "pip install ansible jq"
+  - pip3 install -U ansible jq
 
   # Add ansible.cfg to pick up roles path.
   - printf "[defaults]\nroles_path = ../" > ansible.cfg
@@ -59,11 +57,14 @@ script:
   - yes | ansible-playbook -i tests/inventory tests/test.yml --connection=local
 
   # Run the role/playbook again, checking to make sure it's idempotent.
+  # Skip on "compact" as it will result in 3 changes (create and drop source RP)
   - >
-    yes | ansible-playbook -i tests/inventory tests/test.yml --connection=local
-    | grep -q 'changed=0.*failed=0'
-    && (echo -e "Idempotence test: ${GREEN}pass${NC}" && exit 0)
-    || (echo -e "Idempotence test: ${RED}fail${NC}" && exit 1);
+    if [ "$TEST" != "compact" ]; then
+    result=$(yes | ansible-playbook -i tests/inventory tests/test.yml --connection=local);
+    echo "$result" | grep -q 'changed=0.*failed=0'
+    && (echo -e "Idempotence test: ${GREEN}pass${NC}"; exit 0)
+    || (echo -e "Idempotence test: ${RED}fail${NC}"; echo -e "$result"; exit 1);
+    fi
 
   # TEST = basic
   - >

tasks/influxdb_database.yml

@@ -260,10 +260,30 @@
   when: ifx_mm_defined and (ifx_source_exists or not ifx_source_rp_name)
     and (ifx_cq_recreate or ansible_influx_db_create is changed or mm_item not in ifx_mms or ifx_bf_force)
 
+# count new metrics -> if 0, then skip backfill
+- name: '{{ db_prefix }} Count new metrics in default RP'
+  uri:
+    url: "{{ ansible_influx_url }}/query?db={{ ifx_db.name }}"
+    method: POST
+    body: >
+      q=SELECT COUNT(*)
+      FROM "{{ ifx_db.source.name }}"."{{ ifx_source_rp_name }}"./^({{ ifx_db.measurements|join('|') }})$/
+      WHERE time >= {{ ifx_backfill_start }}000ms
+    return_content: yes
+  register: ansible_influx_newmetrics
+  when: ifx_source_drop and ifx_source_exists
+- name: '{{ db_prefix }} Set count_newmetrics'
+  set_fact:
+    count_newmetrics: "{{ 0 if ansible_influx_newmetrics.json.results[0].series is not defined else
+      ansible_influx_newmetrics.json.results
+      |selectattr('series','defined')|map(attribute='series')|flatten
+      |map(attribute='values')|flatten|select('number')|map('int')|max }}"
+  when: ifx_source_drop and ifx_source_exists
+
 - name: '{{ db_prefix }} Ask to continue and switch default RP (may result in data loss!)'
   pause:
     prompt: "I will now backfill gap and switch default RP and DROP the source! Continue?"
-  when: ifx_source_drop and ifx_source_exists
+  when: ifx_source_drop and ifx_source_exists and count_newmetrics|int > 0
 
 # run twice -> sum up results
 - name: '{{ db_prefix }} Set backfill_start2'
@@ -280,7 +300,7 @@
       GROUP BY *
     return_content: yes
   register: ansible_influx_bf_closegap
-  when: ifx_source_drop and ifx_source_exists
+  when: ifx_source_drop and ifx_source_exists and count_newmetrics|int > 0
 
 - name: '{{ db_prefix }} Backfill again (2) since start (close gap)'
   uri:
@@ -293,7 +313,7 @@
       GROUP BY *
     return_content: yes
   register: ansible_influx_bf_closegap2
-  when: ifx_source_drop and ifx_source_exists
+  when: ifx_source_drop and ifx_source_exists and count_newmetrics|int > 0
 
 - name: '{{ db_prefix }} Get backfill points written'
   set_fact:

tests/vars/compact.yml

@@ -3,6 +3,9 @@
 # backfill 4 days, then make new RP default and drop old RP
 ansible_influx_databases:
   level_0:
+    name: "telegraf"
+    retention_policy: { name: "autogen" }
+  level_1:
     name: "telegraf"
     retention_policy:
       amount: "4"