FEATURE table is not handled properly

[stepanblyschak]

Description

FEATURE table is not properly handled:

• hostcfgd does not handle FEATURE table on system start.
• systemd will start disabled services anyway
• default FEATURE table configuration defined in init_cfg.json will not be migrated to new images
  (e.g. a newer sonic image adds new feature with default disabled state in init_cfg.json, this change will not be loaded in config db if user performed sonic-to-sonic update via cold/fast/warm reboot)

Steps to reproduce the issue:

1. see description

Describe the results you received:

admin@r-tigris-13:~$ show features
Feature    Status
---------  --------
telemetry  disabled
sflow      disabled
admin@r-tigris-13:~$ docker ps
CONTAINER ID        IMAGE                                COMMAND                  CREATED             STATUS              PORTS               NAMES
01de192edf48        docker-sonic-telemetry:latest        "/usr/bin/supervisord"   About an hour ago   Up 3 seconds                            telemetry
61fce64cb3c9        docker-snmp-sv2:latest               "/usr/bin/supervisord"   About an hour ago   Up 3 seconds                            snmp
b3a6424d0876        docker-platform-monitor:latest       "/usr/bin/docker_ini…"   About an hour ago   Up 3 minutes                            pmon
bac1e9d6cb44        docker-sflow:latest                  "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            sflow
93a2eaefa5c1        docker-dhcp-relay:latest             "/usr/bin/docker_ini…"   About an hour ago   Up 3 minutes                            dhcp_relay
067af04fd2b5        docker-router-advertiser:latest      "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            radv
3b9be5993851        docker-nat:latest                    "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            nat
88e4e1919c86        docker-lldp-sv2:latest               "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            lldp
db5eda9a8de0        docker-syncd-mlnx:latest             "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            syncd
8ee29ffef3b9        docker-sonic-mgmt-framework:latest   "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            mgmt-framework
1974d1222d37        docker-teamd:latest                  "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            teamd
e8b5ba9da3f6        docker-orchagent:latest              "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            swss
43437449e4c7        docker-fpm-frr:latest                "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            bgp
2eb615873781        docker-database:latest               "/usr/local/bin/dock…"   About an hour ago   Up 3 minutes                            database

Describe the results you expected:

admin@r-tigris-13:~$ show features
Feature    Status
---------  --------
telemetry  disabled
sflow      disabled
admin@r-tigris-13:~$ docker ps
CONTAINER ID        IMAGE                                COMMAND                  CREATED             STATUS              PORTS               NAMES
61fce64cb3c9        docker-snmp-sv2:latest               "/usr/bin/supervisord"   About an hour ago   Up 3 seconds                            snmp
b3a6424d0876        docker-platform-monitor:latest       "/usr/bin/docker_ini…"   About an hour ago   Up 3 minutes                            pmon
93a2eaefa5c1        docker-dhcp-relay:latest             "/usr/bin/docker_ini…"   About an hour ago   Up 3 minutes                            dhcp_relay
067af04fd2b5        docker-router-advertiser:latest      "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            radv
3b9be5993851        docker-nat:latest                    "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            nat
88e4e1919c86        docker-lldp-sv2:latest               "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            lldp
db5eda9a8de0        docker-syncd-mlnx:latest             "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            syncd
8ee29ffef3b9        docker-sonic-mgmt-framework:latest   "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            mgmt-framework
1974d1222d37        docker-teamd:latest                  "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            teamd
e8b5ba9da3f6        docker-orchagent:latest              "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            swss
43437449e4c7        docker-fpm-frr:latest                "/usr/bin/supervisord"   About an hour ago   Up 3 minutes                            bgp
2eb615873781        docker-database:latest               "/usr/local/bin/dock…"   About an hour ago   Up 3 minutes                            database

Additional information you deem important (e.g. issue happens only occasionally):

**Output of `show version`:**

Distribution: Debian 9.12
Kernel: 4.9.0-9-2-amd64
Build commit: 887ea003
Build date: Sun Feb 16 03:18:30 UTC 2020
Built by: johnar@jenkins-worker-8

Platform: x86_64-mlnx_msn3800-r0
HwSKU: ACS-MSN3800
ASIC: mellanox
Serial Number: MT1937X00527
Uptime: 11:46:59 up 1 min,  1 user,  load average: 6.52, 2.46, 0.90

Docker images:
REPOSITORY                    TAG                 IMAGE ID            SIZE
docker-syncd-mlnx             HEAD.37-887ea003    30f49954e471        383MB
docker-syncd-mlnx             latest              30f49954e471        383MB
docker-router-advertiser      HEAD.37-887ea003    342b19165cc5        287MB
docker-router-advertiser      latest              342b19165cc5        287MB
docker-sonic-mgmt-framework   HEAD.37-887ea003    a6427362690d        424MB
docker-sonic-mgmt-framework   latest              a6427362690d        424MB
docker-platform-monitor       HEAD.37-887ea003    9579180a6838        626MB
docker-platform-monitor       latest              9579180a6838        626MB
docker-fpm-frr                HEAD.37-887ea003    e3c98c87380a        332MB
docker-fpm-frr                latest              e3c98c87380a        332MB
docker-sflow                  HEAD.37-887ea003    4d6c3d5932c0        312MB
docker-sflow                  latest              4d6c3d5932c0        312MB
docker-lldp-sv2               HEAD.37-887ea003    81d22202eb1b        309MB
docker-lldp-sv2               latest              81d22202eb1b        309MB
docker-dhcp-relay             HEAD.37-887ea003    a0ecd89a6a59        297MB
docker-dhcp-relay             latest              a0ecd89a6a59        297MB
docker-database               HEAD.37-887ea003    bf1bcfc91997        287MB
docker-database               latest              bf1bcfc91997        287MB
docker-teamd                  HEAD.37-887ea003    47d427f46304        312MB
docker-teamd                  latest              47d427f46304        312MB
docker-snmp-sv2               HEAD.37-887ea003    c4077a1ed04f        344MB
docker-snmp-sv2               latest              c4077a1ed04f        344MB
docker-orchagent              HEAD.37-887ea003    40a6afd1a39e        330MB
docker-orchagent              latest              40a6afd1a39e        330MB
docker-nat                    HEAD.37-887ea003    4f09c8c75d74        313MB
docker-nat                    latest              4f09c8c75d74        313MB
docker-sonic-telemetry        HEAD.37-887ea003    48294a0583b1        349MB
docker-sonic-telemetry        latest              48294a0583b1        349MB```


    **Attach debug file `sudo generate_dump`:**

    ```
    (paste your output here)
    ```

[jleveque]

Should be resolved by the following PRs:

• [systemd] Relocate all SONiC unit files to /usr/lib/systemd/system #4673
• [hostcfgd] Get service enable/disable feature working #4676
• [hostcfgd] Synchronize all feature statuses once upon start #4714
• [build][systemd] Mask disabled services by default #4721

If any issues persist, please open a new issue.