RPC syncd docker image does not start RPC server automatically

[stepanblyschak]

Description

RPC syncd docker image does not start RPC server automatically;
In the resulting docker syncd rpc image /usr/bin/syncd_init_common.sh has the following line:

ENABLE_SAITHRIFT=0

However, expected is

ENABLE_SAITHRIFT=1

At the same time syncd binary in docker image has RPC support, so changing "ENABLE_SAITHRIFT=0" to "ENABLE_SAITHRIFT=1" starts saithrift server.

After some investigation it looks like the modification time of syncd_init_common.sh from syncd_1.0.0_amd64.deb and syncd-rpc_1.0.0_amd64.deb has the same modifiaction time and size:

root@r-boxer-sw01:/# stat /usr/bin/syncd_init_common.sh
  File: '/usr/bin/syncd_init_common.sh'
  Size: 5438            Blocks: 16         IO Block: 4096   regular file
Device: 803h/2051d      Inode: 269035      Links: 1
Access: (0755/-rwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2019-03-22 09:49:31.000000000 +0000
Modify: 2017-04-12 20:00:00.000000000 +0000
Change: 2019-03-22 09:49:31.718423112 +0000
 Birth: -
root@r-boxer-sw01:/# dpkg -P syncd
(Reading database ... 11224 files and directories currently installed.)
Removing syncd (1.0.0) ...
invoke-rc.d: policy-rc.d denied execution of stop.
Purging configuration files for syncd (1.0.0) ...
root@r-boxer-sw01:/# dpkg -i syncd-rpc_1.0.0_amd64.deb
Selecting previously unselected package syncd-rpc.
(Reading database ... 11214 files and directories currently installed.)
Preparing to unpack syncd-rpc_1.0.0_amd64.deb ...
Unpacking syncd-rpc (1.0.0) ...
Setting up syncd-rpc (1.0.0) ...
invoke-rc.d: policy-rc.d denied execution of start.
Processing triggers for systemd (215-17+deb8u10) ...
root@r-boxer-sw01:/# stat /usr/bin/syncd_init_common.sh
  File: '/usr/bin/syncd_init_common.sh'
  Size: 5438            Blocks: 16         IO Block: 4096   regular file
Device: 803h/2051d      Inode: 269035      Links: 1
Access: (0755/-rwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2019-03-22 09:49:54.000000000 +0000
Modify: 2017-04-12 20:00:00.000000000 +0000
Change: 2019-03-22 09:49:54.226227761 +0000

Since we build docker image with option "--squash" from docker syncd base image, and overwride syncd_init_common.sh by installing syncd-rpc_1.0.0_amd64.deb it looks like squashing process doesn't see a difference and resulting image has old syncd_init_common.sh from base image. See issue : moby/moby#38072

Steps to reproduce the issue:

1. build rpc image
2. run on DUT
3. observe that RPC server is not started

Describe the results you received:
RPC server does not start

Describe the results you expected:
RPC server starts

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

**Output of `show version`:**

```
master 5cfd97a65f70685b1d7c6055a6e7182868d3815a
```

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

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